Abstrict The present invention provides an ultrasonic flow meter that measures
flow volume by determining the flow rate of a liquid from the difference
in propagation times of ultrasonic waves in both directions between
measuring units by providing measuring units having transducer at
an interval in the lengthwise direction on a measuring pipe through
which liquid flows. A pair of mounting members are provided in a
lower case of a case serving as a base at an interval wider than
that of measuring units. The measuring pipe is held by respective
retaining indentations to the outside in the axial direction of
measuring units by facing a left mounting member and a right mounting
member that compose the mounting members. In addition, an insulating
material is filled into the case so as to cover the measuring units
and the measuring pipe.
Claims What is claimed is:
1. An ultrasonic flow meter comprising: a measuring pipe through
which a liquid flows; and two measuring units provided on said measuring
pipe at an interval in its lengthwise direction, and which measures
flow volume by determining the flow rate of a liquid from the difference
in propagation times of ultrasonic waves in both directions between
these measuring units; wherein, said measuring pipe is supported
on a support stand, on which a pair of mounting units are provided
on a base at a wider interval than said measuring units, by retaining
said measuring pipe in said mounting units provided at an interval
to the outside of said measuring units in an axial direction of
said measuring pipe.
2. An ultrasonic flow meter according to claim 1 wherein said
mounting units have a first mounting member and a second mounting
member that are fixed to be mutually facing, and retaining indentations
in the shape of Et circular arc, which form an opening that holds
the outer periphery of said measuring pipe when mutually facing,
are formed in these first and second mounting members.
3. An ultrasonic flow meter according to claim 1 wherein said
mounting members have a lower mounting member and an upper mounting
member fixed to be mutually facing above and below, and retaining
indentations in the shape of a circular arc, which form an opening
that holds the outer periphery of said measuring pipe when mutually
facing, are formed in these lower and upper mounting members.
4. An ultrasonic flow meter according to claim 2 wherein the inner
diameter of said opening formed from said retaining indentations
is slightly smaller than the outer diameter of said measuring pipe.
5. An ultrasonic flow meter according to claim 3 wherein the inner
diameter of said opening formed from said retaining indentations
is slightly smaller than the outer diameter of said measuring pipe.
6. An ultrasonic flow meter according to claim 2 wherein said
retaining indentations are formed to have a rugged surface.
7. An ultrasonic flow meter according to claim 3 wherein said
retaining indentations are formed to have a rugged surface.
8. An ultrasonic flow meter according to claim 4 wherein said
retaining indentations are formed to have a rugged surface.
9. An ultrasonic flow meter according to claim 6 wherein the surface
of said retaining indentations has a rugged shape as a result of
forming engaging grooves along the peripheral direction.
10. An ultrasonic flow meter according to claim 7 wherein the
surface of said retaining indentations has a rugged shape as a result
of forming engaging grooves along the peripheral direction.
11. An ultrasonic flow meter according to claim 8 wherein the
surface of said retaining indentations has a rugged shape as a result
of forming engaging grooves along the peripheral direction.
12. An ultrasonic flow meter according to claim 9 wherein said
engaging grooves are V-shaped grooves.
13. An ultrasonic flow meter according to claim 10 wherein said
engaging grooves are V-shaped grooves.
14. An ultrasonic flow meter according to claim 11 wherein said
engaging grooves are V-shaped grooves.
15. An ultrasonic flow meter according to claim 9 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
16. An ultrasonic flow meter according to claim 10 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
17. An ultrasonic flow meter according to claim 11 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
18. An ultrasonic flow meter according to claim 12 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
19. An ultrasonic flow meter according to claim 13 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
20. An ultrasonic flow meter according to claim 14 wherein a plurality
of said engaging grooves are formed in said retaining indentations
at intervals in the axial direction of the measuring pipe that is
retained.
21. An ultrasonic flow meter according to any one of claims 1 to
20 wherein an insulating means that suppresses the transfer of
heat from the outside is provided covering said measuring units.
22. An ultrasonic flow meter according to claim 21 wherein said
insulating means is composed of an insulating material.
23. An ultrasonic flow meter according to claim 22 wherein said
insulating means is a case that houses said measuring units.
Description BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an ultrasonic flow meter
that measures the flow volume of a liquid flowing through a pipe
using ultrasonic waves.
[0003] 2. Description of the Related Art
[0004] An ultrasonic flow meter is known in the prior art that
uses ultrasonic waves to function as a flow meter that measures
the flow volume of a liquid flowing through a pipe.
[0005] This ultrasonic flow meter provides two measuring units
having a transducer at an interval in the lengthwise direction on
a measuring pipe through which liquid flows. Ultrasonic waves are
emitted from one of the transducers which are then received by the
other transducer. Alternatively, ultrasonic waves are emitted from
the other transducer and then received by the first transducer.
The flow rate of the liquid in the measuring pipe is determined
from the difference in propagation times of these ultrasonic waves,
and flow volume is then measured from this flow rate.
[0006] However, if this ultrasonic flow meter is subjected to vibrations
from the outside between the respective measuring units, measurement
error occurring resulting in fluctuations in characteristics of
the measurement data and causing problems that the flow volume cannot
be measured accurately.
[0007] In addition, since the acoustic velocity, namely the velocity
of the ultrasonic waves, changes according to the temperature of
the liquid, it is necessary to measure flow volume using a conversion
value corresponding to the temperature of the liquid. However, if
ultrasonic waves emitted from the transducer are influenced by factors
other than the temperature of the liquid, such as the outside ambient
temperature, although the flow volume was corrected by converting
according to the temperature of the liquid, there is the problem
that the acoustic velocity is changed due to slight changes in temperature
and the flow volume cannot be measured accurately.
[0008] The following provides a detailed explanation of changes
in the acoustic velocity caused by changes in the temperature of
the liquid using the drawings.
[0009] FIG. 9 is a graph showing the relatLonship between the temperature
(.degree. C.) of water (liquid) and the acoustic velocity (m/s).
In addition, FIG. 10A is a graph showing the change in a reference
flow volume for each passage of time T in the case of a water temperature
of 20.degree. C., while FIG. 10B is a graph showing the output of
the transducers relative to the reference flow volume of FIG. 10A.
In addition, FIG. 11A is a graph showing the change in a reference
flow volume for each passage of time T in the case of a water temperature
of 29.degree. C., while FIG. 11B is a graph showing the output of
the transducers relative to the reference flow volume of FIG. 11A.
[0010] Furthermore, the units of flow volume Q and the reference
flow volume shown in FIGS. 10A and 11A indicate flow volume per
minute (mL/min), and the reference flow volume indicates the flow
volume flowing through the measuring pipe of the ultrasonic flow
meter obtained with a calibrated flow meter.
[0011] Conversion values of flow volume relative to the output
of the transducers are obtained from the graphs shown in FIGS. 9
through 11B.
[0012] It is generally known that the acoustic velocity of ultrasonic
waves output from the transducers changes considerably according
to the temperature of the liquid, and can be represented in the
graph showing the relationship between temperature and the acoustic
velocity of FIG. 9. According to the graph shown in FIG. 9 the
acoustic velocity can be seen to increase the higher the temperature
of the liquid.
[0013] In consideration of this change in the acoustic velocity
due to temperature, as shown in the graph of FIG. 10A, water at
a temperature of 20.degree. C. is allowed to flow in two stages
of 1000 mL and 500 mL per minute from time 0 through the measuring
pipe of the ultrasonic flow meter using the reference flow meter.
For the flow volume of the former first stage, the water is allowed
to flow for time interval T1 and for the flow volume of the latter
second stage, water is allowed to flow for time interval T2 so as
to be continued from the first stage.
[0014] Whereupon, as shown in FIG. 10B, although the output of
ultrasonic waves outputted from the transducers at the ambient temperature
of 24.degree. C. remained nearly level prior to time 0 before the
water flows (see A), it can be seen to decrease suddenly by displacement
D1 (see B) corresponding to the start of water flow (time 0). When
the flow volume of the water changes from 1000 mL/min to 500 mL/min
(see C), the output can be seen to only change slightly by displacement
D2.
[0015] As shown in the drawings, the difference in the output between
displacement D1 and displacement D2 is such that D1.quadrature..quadratur-
e.D2 and the change in the output due to the temperature change
of the difference of 4.degree. C. between the ambient temperature
and the water temperature can be understood to be larger than the
change in the output during the change in flow volume.
[0016] Next, an explanation is provided of the graphs in the case
of allowing water at a water temperature of 29.degree. C. to flow
as shown in FIG. 11 in comparison with the graph of FIG. 10. As
shown in FIG. 11A, water at a temperature of 29.degree. C. is allowed
to flow in two stages at 1000 mL/min and 500 mL/min starting at
time 0 through the measuring pipe of the ultrasonic flow meter using
the reference flow meter. For the flow volume of the former first
stage, the water is allowed to flow for time interval T3 and for
the flow volume of the latter second stage, the water is allowed
to flow for time interval T4 so as to be continued from the first
stage.
[0017] Whereupon, as shown in the graph of FIG. 11B, although the
output of ultrasonic waves output from the transducers at an ambient
temperature of 24.degree. C. was at the same position and remained
nearly level (see E) at the stage of time 0 before the water flowed
in the same manner as FIG. 10A, it can be seen increase suddenly
by displacement D3 (see F) corresponding to the start of the flow
of water (time 0). When the flow volume of water changes from 1000
mL/min to 500 mL/min (see G), the output can be seen to only change
slightly by displacement D4.
[0018] As indicated in the drawings, the difference in output between
displacement D3 and displacement D4 is such that D3.quadrature..quadratur-
e.D4 and the change in the output caused by a temperature change
of the difference of 5.degree. C. between the ambient temperature
and water temperature can be seen to be larger than the change in
the output for the change in flow volume.
[0019] In this manner, in the ultrasonic flow meter, changes in
flow volume are captured in an output region that is much smaller
than the change in the output of the transducers resulting from
a change in the liquid temperature. It can also be understood that
the greater the difference between ambient temperature and liquid
temperature, the larger the change in the output of the transducers.
[0020] Thus, if the liquid temperature is influenced even minimally
by the external ambient temperature, the output of the transducer
changes considerably, and measurement of flow volume at an extremely
small displacement for this output of the transducers has a high
potential to invite measurement error.
[0021] In this manner, in the conventional ultrasonic flow meter,
there were cases in which it was difficult to accurately measure
flow volume depending on the ambient temperature.
SUMMARY OF THE INVENTION
[0022] In consideration of the above circumstances, the object
of the present invention is to provide an ultrasonic flow meter
that is able to minimize effects caused by external vibrations,
and accurately measure flow volume without being affected by outside
temperature.
[0023] In order to achieve the above object, the present invention
provides an ultrasonic flow meter comprising: a measuring pipe through
which a liquid flows, and two measuring units provided on the measuring
pipe at an interval in its lengthwise direction and which measures
flow volume by determining the flow rate of the liquid from the
difference in propagation times of ultrasonic waves in both directions
between these measuring units; wherein, the measuring pipe is supported
on a support stand, on which a pair of mounting units are provided
on a base at a wider interval than the measuring units, by retaining
the measuring pipe in the mounting units provided at an interval
to the outside of the measuring units in an axial direction of the
measuring pipe.
[0024] In this manner, since the measuring pipe is retained and
supported at the outside of the measuring units in the axial direction
of measuring pipe by mounting units provided on the base, external
vibrations can be blocked with the mounting units, thereby allowing
the reliability of measurement between the measuring units, which
are susceptible to the effects of external vibrations, to be enhanced.
[0025] In the ultrasonic flow meter of the present invention, it
is preferable that the mounting units have a first mounting member
and a second mounting member that are fixed to be mutually facing,
and retaining indentations in the shape of a circular arc, which
form an opening that holds the outer periphery of the measuring
pipe when mutually facing, are formed in these first and second
mounting members.
[0026] In this manner, by mutually facing the first and second
mounting members in the state in which the measuring pipe is arranged
in retaining indentations formed in the first and second mounting
members, the outer periphery of the measuring pipe can be retained
extremely easily.
[0027] In the ultrasonic flow meter of the present invention, it
is preferable that the mounting members have a lower mounting member
and an upper mounting member fixed to be mutually facing above and
below, and retaining indentations in the shape of a circular arc,
which form an opening that holds the outer periphery of the measuring
pipe when mutually facing, are formed in these lower and upper mounting
members.
[0028] In this manner, by mutually facing the upper and lower mounting
members in the state in which the measuring pipe is arranged in
the retaining indentations formed on the upper and lower mounting
members, the outer periphery of the measuring pipe can be retained
extremely easily.
[0029] In the ultrasonic flow meter of the present invention, it
is preferable that the inner diameter of an diameter of an opening
which is composed by the retaining indentations is slightly smaller
than the outer diameter of the measuring pipe.
[0030] In this manner, since the opening comprised by the retaining
indentations formed by mutually facing each mounting member is formed
to have a diameter that is slightly smaller than the outer diameter
of the measuring pipe, the measuring pipe can be reliably retained
by both mounting members.
[0031] In the ultrasonic flow meter of the present invention, it
is preferable that the retaining indentations are formed to have
a rugged surface.
[0032] In this manner, since the retaining indentations are formed
to have a rugged surface, the measuring pipe can be reliably retained,
and the effects of external vibrations can be further reduced.
[0033] In the ultrasonic flow meter of the present invention, it
is preferable that the surface of the retaining indentations has
a rugged shape as a result of forming engaging grooves along the
peripheral direction.
[0034] In this manner, since the surface of the retaining indentations
is formed to have a rugged shape as a result of forming engaging
grooves along the peripheral direction, vibrations in the measuring
pipe in the axial direction can be reliably blocked by the engaging
grooves.
[0035] In the ultrasonic flow meter of the present invention, it
is preferable that the engaging grooves are V-shaped grooves.
[0036] In this manner, since the engaging grooves are V-shaped
grooves, the outer peripheral surface of the measuring pipe reliably
engages with the engaging grooves, thereby reliably retaining the
measuring pipe in the mounting members.
[0037] In the ultrasonic flow meter of the present invention, it
is further preferable that a plurality of the engaging grooves are
formed in the retaining indentations at intervals in the axial direction
of the measuring pipe that is retained.
[0038] In this manner, since a plurality of engaging grooves are
provided arranged in the axial direction, vibrations transmitted
to the measuring pipe can be blocked even more reliably.
[0039] In the ultrasonic flow meter of the present invention, it
is preferable that an insulating means that covers the measuring
units and suppresses the transfer of heat from the outside is provided.
[0040] In this manner, since the measuring units are covered by
the insulating means, it is difficult for external heat to transfer
to the measuring units, and the temperature of the measuring units
is maintained. In other words, the temperature of the liquid flowing
through the measuring pipe constitutes the main effect on the measuring
units. Therefore, the temperature of the liquid flowing through
the measuring units is no longer affected by the external ambient
temperature, and flow volume can be measured accurately from changes
in the acoustic velocity of ultrasonic waves in accordance with
the liquid temperature.
[0041] In the ultrasonic flow meter of the present invention, it
is further preferable that the insulating means is composed of an
insulating material.
[0042] In this manner, since the insulating means is composed of
the insulating material, heat insulation is carried out more effectively,
and for example, the measuring units can be covered according to
the shape of the measuring units to promote more effective heat
insulation. Therefore, it is possible to accurately measure flow
volume without the liquid temperature being affected by the external
temperature.
[0043] In the ultrasonic flow meter of the present invention, it
is further preferable that the insulating means is a case that houses
the measuring units.
[0044] In this manner, the measuring units are removed from transfer
of heat from the outside by being housed, and therefore, flow volume
can be measured accurately by blocking the effects of the external
ambient temperature. In addition, the measuring units can be protected
by the case, and the reliability and durability of the ultrasonic
flow meter are improved. The case preferably uses a material having
insulating action and a low coefficient of heat transfer, and preferably
uses a material such as SUS.
BRIEF EXPLANATION OF THE DRAWINGS
[0045] FIG. 1 is a perspective view for explaining the structure
of the ultrasonic flow meter in a first embodiment of the present
invention.
[0046] FIG. 2 is a side view for explaining the structure of the
ultrasonic flow meter in the first embodiment of the present invention.
[0047] FIG. 3 is an exploded cross-sectional view for explaining
the structure of the mounting unit that fixes the ultrasonic flow
meter in the first embodiment of the present invention to the support
stand.
[0048] FIG. 4 is an overhead view for explaining the structure
of the mounting member of the mounting unit of FIG. 3.
[0049] FIG. 5 is a partial cross-sectional view for explaining
the structure of the fixing portion of the mounting unit of FIG.
3.
[0050] FIG. 6 is a partially enlarged cross-sectional view for
explaining the structure of the fixing portion of the mounting unit
of FIG. 3.
[0051] FIG. 7A is an exploded view for explaining the structure
of the ultrasonic flow meter in a second embodiment of the present
invention
[0052] FIG. 7B is a cross-sectional view of the ultrasonic flow
meter of FIG. 7A as viewed from the cross-section taking along the
axis of a measuring pipe.
[0053] FIG. 8A is a perspective view for explaining the structure
of the ultrasonic flow meter showing a variation of the second embodiment.
[0054] FIG. 8B is a cross-sectional view of the ultrasonic flow
meter of FIG. 8A as viewed from cross-section H-H taken along the
axis of the measuring pipe.
[0055] FIG. 9 is a graph showing the relationship between water
temperature and acoustic velocity.
[0056] FIG. 10A is a graph of experimental data showing the change
in reference flow volume during time T at a water temperature of
20.degree. C.
[0057] FIG. 10B is a graph of experimental data showing the change
in the output of the transducer relative to the reference flow volume
shown in FIG. 10A.
[0058] FIG. 11A is a graph of experimental data showing the change
in reference flow volume during time T at a water temperature of
29.degree. C.
[0059] FIG. 11B is a graph of experimental data showing the change
in the output of the transducer relative to the reference flow volume
shown in FIG. 11A.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0060] The following provides an explanation of the ultrasonic
flow meter of the embodiments of the present invention with reference
to the drawings.
[0061] [First Embodiment]
[0062] The following provides an explanation of a first embodiment
of the ultrasonic flow meter as claimed in the present invention.
[0063] In FIGS. 1 and 2 reference symbol 1 indicates an ultrasonic
flow meter. This ultrasonic flow meter 1 is formed from a synthetic
resin having superior chemical resistance such as vinyl chloride
or fluororesin, and has a measuring pipe 2 through which a liquid
flows, and two measuring units 3 provided at an interval in the
lengthwise direction on this measuring pipe 2.
[0064] The measuring units 3 employ a structure in which a transducer
5 is tightly adhered to the outer periphery of the measuring pipe
2 and its outer periphery is covered by the retaining tube 6. Furthermore,
reference symbol 8 in the drawings indicates lead wires of transducer
5.
[0065] The ultrasonic flow meter 1 composed in the manner described
above is supported on a support stand 11. This support stand 11
has a base 13 provided with legs 12 extending downward, and mounting
units 14 provided on the upper surface of base 13 near both ends,
and ultrasonic flow meter 1 is respectively supported by these mounting
units 14 at locations farther to the outside of the measuring unit
3 in the an axial direction of the measuring pipe 2.
[0066] As shown in FIG. 3 each mounting unit 14 has a lower mounting
member 14a fixed on base 13 and an upper mounting member 14b fixed
to the upper portion of this lower mounting member 14a.
[0067] Retaining indentations 21 in the shape of a circular arc
are formed on the respective opposing faces of the lower mounting
member 14a and the upper mounting member 14b, and by mutually facing
the lower mounting member 14a and the upper mounting member 14b,
a opening 22 having circular shape is formed by each retaining indentation
21.
[0068] A pair of threaded holes 23 are formed in the lower surface
of lower mounting member 14a, and by screwing bolts 25 that are
inserted from the lower surface of the base 13 through mounting
holes 24 formed in the base 13 into these threaded holes 23 the
lower mounting member 14a is fastened to the base 13.
[0069] In addition, a pair of coupling threaded holes 26 are formed
in the upper surface of the lower mounting member 14a, and insertion
holes 27 are formed in the upper mounting member 14b that are continuous
with the coupling threaded holes 26 when installed on the upper
portion of the lower mounting member 14a.
[0070] By installing the upper mounting member 14b on the upper
portion of the lower mounting member 14a, inserting mounting bolts
28 into the insertion holes 27 of upper mounting member 14b in the
state in which the measuring pipe 2 of the ultrasonic flow meter
1 is arranged in the opening 22 comprised by the retaining indentations
21 and screwing the mounting bolts 28 into the coupling threaded
holes 26 the lower mounting member 14a and the upper mounting member
14b are fastened together, and then the measuring pipe 2 of the
ultrasonic flow meter 1 is held in the opening 22 comprised by the
retaining indentations 21.
[0071] Here, the inner diameter of the opening 22 comprised by
the retaining indentations 21 of the lower mounting member 14a and
the upper mounting member 14b is made to be slightly smaller than
the outer diameter of the measuring pipe 2.
[0072] Moreover, as shown in FIGS. 4 and 5 a plurality of V-shaped
engaging grooves 31 are formed along the peripheral direction at
intervals in the axial direction in the retaining indentations 21
of the lower mounting member 14a and the upper mounting member 14b.
[0073] As a result, when the measuring pipe 2 of the ultrasonic
flow meter 1 is fixed by these mounting units 14 as a result of
the outer periphery of the measuring pipe 2 engaging with the engaging
grooves 31 of the retaining indentations 21 of the lower mounting
member 14a and the upper mounting member 14b as shown in FIG. 6
the measuring pipe 2 is reliably held, and displacement of the measuring
pipe 2 in the axial direction of the measuring pipe 2 or in any
of the other four directions is reliably prevented.
[0074] In this manner, according to the above-mentioned ultrasonic
flow meter, since the measuring pipe 2 is held and supported by
the mounting units 14 provided on the base 13 at locations farther
to the outside in the axial direction than measuring units 3 provided
at an interval, external vibrations can be blocked with the mounting
members 14. Therefore, it is possible to enhance the reliability
of measurement between the measuring units 3 which are susceptible
to the effects of external vibrations.
[0075] Moreover, by facing the lower mounting member 14a and the
upper mounting member 14b in the state in which the measuring pipe
2 is arranged in the retaining indentations 21 formed in the lower
mounting member 14a and the upper mounting member 14b, the outer
periphery of the measuring pipe 2 can be held extremely easily.
[0076] In addition, since the opening 22 comprised by the retaining
indentations 21 formed by the facing lower mounting member 14a and
the upper mounting member 14b is formed to have a slightly smaller
diameter than the outer diameter of the measuring pipe 2 the measuring
pipe 2 can be reliably held by the lower mounting member 14a and
the upper mounting member 14b.
[0077] Moreover, since the surface of the retaining indentations
21 is formed in a rugged shape by a plurality of engaging grooves
31 arranged in the axial direction along their peripheral direction,
vibrations to the axial direction in the measuring pipe 2 can be
reliably blocked by the engaging grooves 31.
[0078] Moreover, since the engaging grooves 31 are in the form
of V-shaped grooves, the outer peripheral surface of the measuring
pipe 2 can reliably engage with engaging grooves 31 thereby allowing
measuring pipe 2 to be even more reliably held in mounting units
14.
[0079] [Second Embodiment]
[0080] The following provides an explanation of a second embodiment
of the ultrasonic flow meter as claimed in the present invention
using FIGS. 7A and 7B.
[0081] FIGS. 7A and 7B are drawings showing an ultrasonic flow
meter 1a in the present embodiment, with FIG. 7A being an exploded
view of the ultrasonic flow meter 1a, and FIG. 7B being a cross-sectional
view as viewed from the cross-sectional parallel to the axis of
a measuring pipe 2 of the ultrasonic flow meter 1a.
[0082] In the drawing, reference symbol 4 indicates a tightly adhered
tube, 14 indicates a mounting unit composed of a lower mounting
member 14a and an upper mounting member 14b, 50 indicates a case
(insulating means) composed of a lower case 51 serving as a base
and an upper case 52 and 53 and 54 indicate respective insulating
materials (insulating means).
[0083] Furthermore, since other reference symbols are the same
as in the ultrasonic flow meter explained in the above first embodiment,
their explanation is omitted.
[0084] The case 50 shown in FIG. 7B is composed by the combining
lower case 51 formed into the shape of a "U" by bending,
and the upper case 52 formed into the shape of a flat plate to
match the opening in the top of the lower case 51. This case 50
is made of SUS (Stainless Steel) material having a comparatively
poor heat transfer rate, and its total length has a length that
is equal to or greater than the interval between the measuring units
3 provided at a prescribed interval.
[0085] The lower mounting members 14a, which are formed at roughly
half the height of the case 50 are fixed at both ends in the lengthwise
direction of the lower case 51 so as to each be housed within the
lower case 51 in the same manner as the attachment to the base 13
shown in the first embodiment. The retaining indentations 21 in
the shape of a circular arc are formed in the upper surface of the
lower mounting members 14a, and by mutually facing the opposing
retaining indentations 21 of the upper mounting member 14a, openings
are formed by the respective retaining indentations 21.
[0086] A pair of bolt insertion holes 27 for the mounting bolts
28 that fasten the upper mounting members 14b and the lower mounting
members 14a are formed in the upper surface of the upper mounting
member 14a in the same manner as the first embodiment, and a pair
of bolt insertion holes 55a for upper cover mounting bolts 55 for
attaching the upper cover 52 are also formed in the upper surface
of the upper mounting member 14a. Furthermore, a pair of insertion
holes 55b to pass the upper cover mounting bolts 55 are each formed
in the upper cover 52 as well.
[0087] The insulating materials 53 and 54 divided into two parts
above and below each other, use foaming polystyrol for their material,
and are formed to a size such that they can be housed in the space
inside the case 50 when combined. Indentation 53b in the shape of
a circular arc is formed in the upper surface of lower insulating
material 53 to match the shape of measuring pipe 2 while indentations
53a in the shape of a circular arc having a large radius are formed
in the upper surface of lower insulating material 53 to match the
positions of both measuring units 3.
[0088] In addition, indentations are formed in upper insulating
member 54 as well to match the shapes of the measuring pipe 2 and
the measuring units 3 in the same manner as lower insulating member
53.
[0089] In the measuring unit 3 differs from the measuring unit
3 shown in the first embodiment, the transducer 5 is fixed to the
outside of the measuring pipe 2 over the tightly adhered tube 4.
In this case, ultrasonic waves emitted or received from the transducer
5 are transmitted through the tightly adhered tube 4 fixed by being
tightly adhered to the outside of the measuring pipe 2. The tightly
adhered tube 4 is fixed by, for example, a gel-like adhesive.
[0090] The ultrasonic flow meter 1a assembled as shown in FIG.
7B is formed to have an external shape such that both the measuring
units 3 of the measuring pipe 2 are covered by the case 50 and
is further composed so that both the measuring units 3 and the measuring
pipe 2 between them housed inside the case 50 are covered by the
insulating materials 53 and 54.
[0091] As a result, the inside and outside of the ultrasonic flow
meter 1a are isolated by the case 50 making them thermally insulated,
and the space between the measuring units 3 is further isolated
from the outside by insulating material, thereby making them thermally
insulated.
[0092] According to the ultrasonic flow meter 1a in the present
embodiment explained above, since the measuring pipe 2 is held and
supported by the mounting units 14 provided inside the case 50 father
to the outside in the axial direction than the measuring units 3
provided at an interval, vibrations from the outside can be blocked
by the mounting units 14 and as a result, the reliability of measurement
between the measuring units 3 which are susceptible to the effects
of external vibrations, can be enhanced.
[0093] In addition, since liquid flowing inside the measuring pipe
2 is no longer affected by external ambient temperature due to the
case 50 and the insulating materials 53 and 54 the temperature
of the liquid no longer changes in both measuring units 3 thereby
making it possible to accurately measure flow volume corresponding
to the temperature of the liquid.
[0094] Furthermore, although a constitution in which the insulating
materials 53 and 54 are provided inside the case 50 has been explained
for the ultrasonic flow meter 1a explained in the present embodiment,
this should not be interpreted as being limited to this, but rather
only the case 50 may be provided as an insulating means of measuring
pipe 2. According to this, although insulating effects decrease
as compared with the present embodiment, if installed in a location
where there is little change in ambient temperature, this ultrasonic
flow meter is still capable of fulfilling its function. Furthermore,
since the insulating materials 53 and 54 are not used, production
costs can be reduced.
[0095] In addition, an ultrasonic flow meter 1b shown in FIGS.
8A and 8B may be used as a variation of the present embodiment.
FIGS. 8A and 8B are drawings explaining the structure of the ultrasonic
flow meter 1b showing a variation of the present embodiment, with
FIG. 8A being a perspective view showing its external form, and
FIG. 8B being a cross-sectional view taking along the axial direction
the of measuring pipe 2 in cross-section H-H of FIG. 8A.
[0096] Reference symbol 51' indicates a lower case in the shape
of the letter "U" similar to the first embodiment, 52'
indicates an upper cover in the shape of the letter "L",
60 indicates a protective cover installed so as to cover the measuring
units 3 and the outer periphery of the measuring pipe 2 between
the both measuring units 3 and 61 indicates an insulating material
(insulating means) filled inside lower case 51'. In addition, reference
symbol S indicates a space for processing, wiring connections formed
by the upper cover 52', while reference symbols J indicate wiring
connections between lead wires 8 and cables 8a.
[0097] The lower case 51' has a opening (see reference symbol K)
formed on the right side so as to cover the axis of the measuring
pipe 2 in the drawings, and a wall 52b' that composes the upper
cover 52' is attached to as to cover this opening.
[0098] In addition, the mounting units 14' are provided on both
ends of the lower case 51' similar to the ultrasonic flow meter
1 a explained in FIGS. 7A and 7B. As shown in FIG. 8A, the mounting
units 14' are divided into two sections to match the direction of
orientation of the opening of the lower case 51', with a right mounting
member 14b' (second mounting member) being provided on the side
of the opening of the lower case 51', and a left mounting member
14a' (first mounting member) being provided at the position that
faces the right mounting member 14b' with measuring pipe 2 interposed
between. In other words, the ultrasonic flow meter 1b referred to
here is arranged nearly equivalent to the state in which the ultrasonic
flow meter 1a shown in FIG. 7 is rotated by 90 degrees about the
axis of the measuring pipe 2 as the center, and the measuring pipe
2 is fixed by the mounting units 14'.
[0099] In addition, lead wire guide holes 51a' are formed in an
upper wall 51b' that composes lower case 51', respectively arranged
nearly directly above the measuring units 3 on both sides. As a
result, the lead wires 8 of the transducer 5 are wired outside of
the lower case 51' through the lead wire guide holes 51a', and the
ends of the lead wires 8 are positioned in the space S formed by
the upper cover 52' for processing the wiring connections.
[0100] The upper cover 52' has an L-shaped cross-section that intersects
the axis of the measuring pipe 2 with one section being composed
by a wall 52b' in the shape of a flat plate, and the other section
being composed by a wall 52c' that is perpendicular to the wall
52b' and in the shape of a vat. A case 50' is then assembled by
the plate-shaped wall 52b' being fixed to the right mounting member
14b' of the lower case 51' by a plurality of upper cover fastening
bolts 55'.
[0101] Cable guide holes 52a' are formed in the vat-shaped wall
52c' so as to oppose the lead wire guide holes 51a' formed in the
lower case 51'. In addition, the space S for processing wiring connections
is formed inside the vat-shaped wall 52c' as a result of combining
the lower case 51'.
[0102] The space S is an empty space that houses wiring connections
J that are formed by processing the wiring connections of the lead
wires 8.
[0103] The lead wires 8 have a prescribed length from the transducer
5 and are required to be extended in processes of composing the
ultrasonic flow meter 1b. Consequently, the lead wires 8 are connected
with cables 8a capable of reliably incorporating weak signals to
a measuring amplifier and so forth with the wiring connections J,
and are wired outside of the case 50' from the cable guide holes
52a' after being fixed in the vicinity of the lead wire guide holes
51a'.
[0104] Thus, the wiring connections J of the lead wires 8 are located
within the space S for processing wiring connections. Naturally,
the upper cover 52' is attached to the lower case 51' after having
filled the insulating material 61 to be described later, and at
the time of completion of connection processing of the lead wires
8 and the cables 8a.
[0105] In addition, the present variation also employs a structure
in which the insulating material 61 is provided within the case
50'. In this variation, a structure is shown in which the insulating
material 61 is filled after fixing the measuring pipe 2 with the
mounting units 14' in the lower case 51', and partly covering the
measuring units 3 and the measuring pipe 2 with protective cover
60 made of plastic and so forth.
[0106] The following provides a more detailed explanation of the
constitution of the insulating material 61 and the filling work.
Since the measuring units 3 and the measuring pipe 2 are important
components for measuring flow volume, it is necessary that they
be protected from the filling work of the insulating material 61
described later. In order to protect these components, the measuring
units 3 and the measuring pipe 2 are covered by a protective cover
60 made of, for example, polypropylene resin. A similar resin may
be used to cover the area around the lead wires 8 and the gaps of
the case 50'.
[0107] After providing the protective cover 60 on the measuring
units 3 the insulating material 61 in the form of foaming polystyrol
and so forth is filled into the lower case 51'. As a result, the
insulating material 61 is filled throughout all portions of the
lower case 51', and thermal insulating action is obtained for the
measuring units 3 and the measuring pipe 2 between the both measuring
units 3.
[0108] Furthermore, the insulating material 61 may be partly filled
into one side of the case 50' formed to match the shape of the protective
cover 60 in advance, and then the protective cover 60 provided with
the remaining insulating material 61 may be inserted inside the
case 50'.
[0109] According to such an ultrasonic flow meter 1b, in addition
to improving the rigidity of the case 50' and enhancing its strength,
the thermal insulation properties can also be further improved.
In addition, since the insulating material 61 can be easily provided
within the case 50', it is not necessary to form insulating material
to match the shapes of the measuring units 3 and the measuring pipe
2 thereby making it possible to suppress production costs. In addition,
the wiring connections J of the lead wires 8 are located between
the outside of the insulating material 61 and the inside of upper
cover 52', thereby making it possible to realize simplification
of connection processing and protection of the wiring connections
J.
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